This state represents the natural range of variability under pristine conditions. Community phase changes are driven by natural disturbances such as periodic drought, wildfire and insect attack. This site experiences light to moderate grazing by wildlife. Timing of disturbances combined with weather events determines plant community dynamics.
Introduced annuals such as red brome, schismus and redstem stork's bill have invaded the reference plant community and have become a dominant component of the herbaceous cover. This invasion of non-natives is attributed to a combination of factors including: 1) surface disturbances, 2) changes in the kinds of animals and their grazing patterns, 3) drought, and 4) changes in fire history. These non-natives annuals are highly flammable and promote wildfires where fires historically have been infrequent.
A biotic threshold has been crossed, with the introduction of non-native annuals that cannot be removed from the system. The presence of non-natives has the potential to alter disturbance regimes significantly from their natural or historic range of disturbances.
Introduction of non-native species due to anthropogenic disturbances including OHV use, dry land farming, grazing, linear corridors, mining, military operations, and settlements.
Model keys
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The Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.